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This paper describes the use of innovative, nanosilica containing epoxy powder coatings for the corrosion protection of steel. Two types of nanosilica particles (hydrophilic -HL- and hydrophobic -HB-) were mixed by ball milling with the powders (0.75 wt.%). The adequate homogeneity and embedding of nanoparticles were verified by transmission electron microscopy. The corrosion performance of the coatings as-received, and with HL and HB additions, were analyzed in 3.5 wt.% NaCl solutions. The mechanism and rate of delamination of defective coatings under drops simulating atmospheric conditions were analyzed by Scanning Kelvin Probe measurements for 30 d. The results show that the corrosion attack progresses through a cathodic delamination mechanism. Besides, fully-immersed samples, with and without defects, were monitored by electrochemical impedance spectroscopy. In defective coatings under these conditions, the occurrence of anodic undermining is proved. The results obtained reveal that the corrosion driven coating failure is delayed in the case of the epoxy coatings containing nanosilica. This delay is larger in the case of HB additions than HL additions in both atmospheric and immersion conditions. The corrosion mechanism observed is dependent upon exposure conditions. It is proposed that the nanoparticles delay water absorption, thus delaying corrosion attack., Accepted Author Manuscript, (OLD) MSE-6

The development of broadband and ultra-compact optoelectronic devices relies on the possibility of fabricating bright and tunable emitters at the nanoscale. Here we show emission from EuOx (1 ≤ x < 1.4) thin films on Silicon formed by nanocrystals with average sizes in the range of 5 nm. The photoluminescence emission of the nano-EuOx films is tunable as a function of the oxygen concentration changing from a green broadband Eu2+−related emission to a narrow red Eu3+−related emission. To achieve these results has been instrumental the use of a new methodology specially designed to achieve high quality europium oxide films whose compositional properties are controlled by the growth base pressure and preserved thanks to a chemically stable and transparent cover layer of Al2O3. Our findings confirm the outstanding p otential of nanostructured EuOx films as “onecompound” optical elements with tunable emission properties for their implementation in integrated silicon-based devices

Gas-phase synthesis of nanoparticles with different structural and chemical distribution is reported using a circular magnetron sputtering in an ion cluster source by applying high-power impulses. The influence of the pulse characteristics on the final deposit was evaluated on Au nanoparticles. The results have been compared with the more common direct current approach. In addition, it is shown for the first time that high-power impulses in magnetron based gas aggregation sources allows the growth of binary nanoparticles, CoAu in this case, with a variety of crystalline and chemical arrangements which are analyzed at the atomic level.

Combination of complementary imaging techniques, like hybrid PET/MRI, allows protocols to be developed that exploit the best features of both. In order to get the best of these combinations the use of dual probes is highly desirable. On this sense the combination of biocompatible iron oxide nanoparticles and 68Ga isotope is a powerful development for the new generation of hybrid systems and multimodality approaches. Our objective was the synthesis and application of a chelator-free 68Ga-iron oxide nanotracer with improved stability, radiolabeling yield and in vivo performance in dual PET/MRI. We carried out the core doping of iron oxide nanoparticles, without the use of any chelator, by a microwave-driven protocol. The synthesis allowed the production of extremely small (2.5 nm) 68Ga core-doped iron oxide nanoparticles. The microwave approach allowed an extremely fast synthesis with a 90% radiolabeling yield and T1 contrast in MRI. With the same microwave approach the nano-radiotracer was functionalized in a fast and efficient way. We finally evaluated these dual targeting nanoparticles in an angiogenesis murine model by PET/MR imaging.

The nucleation of SrTiO3 three-dimensional (3D) islands and nanorings on Si substrates via a novel metalorganic decomposition (MOD) process has been investigated as a function of temperature and solution concentration of the SrTi(OC3H7)6 precursor. Quantitative analysis of island density and size distribution by atomic force microscopy (AFM) has revealed the existence of a nucleation regime at solution concentrations below 5 × 10-3 M, in which the critical nucleus is a trimer and a coalescence regime at higher concentrations, dominated by growth of immobile clusters. Nanorings form preferentially under high supersaturation conditions and their size distribution is consistent with a dynamic coalescence. On the basis of recent theoretical models (Gill, 2012), we have proposed that the island-to-nanoring transition in the SrTiO3/Si system occurs above a critical size as a result of a competition between energetic and kinetic factors. The combination of high-resolution transmission electron microscopy (HRTEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) has shown that the monocrystalline SrTiO3 nanoclusters grow pseudomorphically on the Si substrate and exhibit a strain-induced tetragonal lattice distortion.

The crystallization and structure of Fe-B nanoparticles (NPs) of different sizes formed in a single process by gas aggregation from Fe80B 20 targets were analyzed by transmission electron microscopy. It is concluded that all NPs are covered by an amorphous Fe-B shell while the crystal structure of the NPs core depends on their size. Large NPs with diameters ≥30 nm are monocrystalline tetragonal Fe3B, small diameter NPs (≤20 nm) are completely amorphous whereas in middle size NPs, with diameters between 20 and 30 nm, difference Fe-B phases (tetragonal Fe3B and orthorhombic FeB) together with defaulted areas are observed. This work opens new possibilities to produce Fe-B NPs tailoring their magnetic properties by controlling their size and composition. © 2013 Springer Science+Business Media New York.

This work reports changes in the structural properties of sputtered GaAs layers deposited on Si (100) substrates induced by thermal annealing under different arsine atmospheres. The effects of the AsH3 partial pressure (P AsH3 ) and of the annealing temperature in the GaAs layer properties were analyzed by means of in situ reflectance spectroscopy, in situ transient reflectance at 2.65 eV, X-ray diffraction and atomic force microscopy. The results obtained reveal a direct correlation between the AsH3 partial pressure and the evolution of the GaAs surface morphology as well as the annihilation of As clusters formed during the sputtering procedure., Peer Reviewed, Postprint (published version)

Atomic hydrogen modification of the surface energy of GaAs (110) epilayers, grown at high temperatures from molecular beams of Ga and As4, has been investigated by friction force microscopy (FFM). The reduction of the friction force observed with longer exposures to the H beam has been correlated with the lowering of the surface energy originated by the progressive de-relaxation of the GaAs (110) surface occurring upon H chemisorption. Our results indicate that the H-terminated GaAs (110) epilayers are more stable than the As-stabilized ones, with the minimum surface energy value of 31 meV/Å2 measured for the fully hydrogenated surface. A significant reduction of the Ga diffusion length on the H-terminated surface irrespective of H coverage has been calculated from the FFM data, consistent with the layer-by-layer growth mode and the greater As incorporation coefficient determined from real-time reflection high-energy electron diffraction studies. Arsenic incorporation through direct dissociative chemisorption of single As4 molecules mediated by H on the GaAs (110) surface has been proposed as the most likely explanation for the changes in surface kinetics observed. © 2013 AIP Publishing LLC.

The invention is based on the observation by the inventors that modification of the surface topography of materials through the creation of an ordered network of cavities filled with another material with a different refractive index generates photonic bands at the surface of the material that alter the refractive index of the material on which said cavities are created. Depending on the angle of incidence and the wavelength of the light, this change in refractive index can facilitate or inhibit the transmission and reflection of the light. On the basis of this new observed property, the topography of a solar cell was modified by creating an ordered network of cavities filled with air, and it was confirmed that there was an increased generation of electricity from incident light than in a solar cell with the same characteristics but without a modified surface topography., La invención es basada en la observación de los inventores que la modificación de la topografía de la superficie de materiales de tipo a través de la creación de una red ordenada de las cavidades llenadas con otro material de tipo con un diferente índice de refracción genera a bandas photonic en la superficie del material que alteran el índice de refracción del material de tipo en el cual dijo el son de las cavidades creado. Dependiendo del ángulo de incidencia y de la longitud de onda de la luz, este cambio en bote del índice de refracción facilita o inhibe la transmisión y la reflexión de la luz. En base de esta propiedad observada nueva, la topografía de una célula solar fue modificada creando una red ordenada de las cavidades llenadas con aire, y fue confirmado que había una generación creciente de electricidad de la luz incidente que en una célula solar con las mismas características pero sin una topografía modificada de la superficie.

A single-junction germanium solar cell with a photonic crystal nanostructured surface has been developed. The solar cell comprises a Ge p-n junction and an InGaP window layer. The InGaP window layer has been nanopatterned with an extended photonic crystal structure consisting on a triangular lattice of holes with submicronic sizes. Enhancements of the external quantum efficiency of 22% for a wide range of wavelengths and up to a 46% for specific wavelengths have been measured, which implies an increase in photocurrent between 11% and 22%. A clear correlation with the area of photonic crystal patterned has been observed.